The invention disclosed herein generally embodies a gravity flow water filtration cartridge with a novel sieve system. The water filtration cartridge is to be used with any known water filtration device. Examples of such devices include gravity flow systems, such as pour-through pitchers, filtering water bottle, countertop system.
Pour-through pitcher systems typically include an upper reservoir for receiving unfiltered water, a lower reservoir for receiving and storing filtered water, and a filtration cartridge with an inlet at its top and outlet at its bottom, through which cartridge, water flows from the upper reservoir to the lower reservoir. Countertop systems typically include a larger rectangular tank with a spigot for draining filtered water into a glass or pan. Both pitcher and countertop systems use gravity to move the unfiltered water in the top reservoir down through a water filtration cartridge and into the lower reservoir where the filtered water remains until it is used.
The water filtration cartridge typically employed in a gravity flow system is composed of a sieve system and a housing bottom, such as a barrel. The barrel is filled with filtration media and the sieve system is sealed to the barrel. The filtration media is typically granular, such as activated carbon. Other components may be combined to enhance water filtration capability, such as ion exchange resin, zeolite, ceramics, and others known in the art.
A problem associated with using granular filtration media in such a gravity flow cartridge, is that air gets trapped in-between the particles of filtration media and in the headspace of the cartridge barrel. The “headspace” is the area above the fill line of the filtration media and up to the bottom of the sieve system. This air must be vented from the cartridge as water is filtered or water flow will be slow or completely stop. In prior art systems, the air in the water filtration cartridge is expelled through vents in the top of the filter. The size of the vents is critical. The vent size must be small enough to contain the carbon in the filter and big enough to allow the air to escape. Prior art systems have large vent holes to properly vent the air, and thus, are limited to a minimum carbon particle size.
Prior art water filtration cartridges typically employ granular filtration media the size of about 18×40 U.S. mesh (1000 μm to 425 μm). This size range has limited contaminant removal capability due to particle size and packing geometry of the granules. Better filtration capability can be achieved using smaller size filtration media, such as 20×80 U.S. mesh (850 μm to 180 μm). However, smaller media is difficult to retain in the cartridge housing. The smaller media is typically swept out of the cartridge through the air vent holes in the cap and ends up in the un-filtered water of the upper reservoir.
It would be useful to have a gravity flow water filtration cartridge that exhibits both good water flow rates and high containment reduction.